CO3W3C Fishbone-Like Hard Phase-Reinforced Fe-Based Wear-Resistant Coating and Preparation Thereof

ABSTRACT

A Co 3 W 3 C fishbone-like hard phase-reinforced Fe-based wear-resistant coating and the preparation thereof, which belongs to the field of a wear-resistant coating on the surface of a material and a preparation method thereof. The wear-resistant coating comprises: 1.89-3.77% of C, 5.4-11.7% of Cr, 3.3-7.15% of Ni, 28.81-57.83% of W, 4.2-8.4% of Co, 0.03-0.065% of Si and the balance of Fe. The preparation process of the wear-resistant coating comprises: (1) before plasma cladding, pretreating a matrix; (2) pretreating an iron-based alloy powder; and (3) adjusting the process parameters of plasma cladding, preparing a cladding layer with a predetermined width and a predetermined thickness, and naturally cooling same down in air. The wear-resistant coating is simple in process; the prepared cladding layer has a strong metallurgical bonding property with the matrix structure, so that the best performance matching between the ceramic phase of the cladding layer and the matrix can be achieved; a fishbone-like hard phase Co 3 W 3 C has a very high hardness value and plays the role of a framework in the frictional process to reduce the wear of the matrix structure, thereby achieving an excellent wear resistance; plasma cladding is convenient to operate, and can be automatized; and the prepared wear-resistant layer is high in size precision and can be widely applied to surface modification of mechanical parts.

TECHNICAL FIELD

The present invention relates to a material surface wear-resistantcoating and preparation thereof, and particularly to a Co₃W₃Cfish-bone-shape hard-phase reinforced Fe-based wear-resistant coatingand method for preparing the same.

BACKGROUND ART

During use of a mechanical part, most of the wear occurs on the surfacepart of a workpiece, and especially in a severe working environment,e.g., high corrosion, high friction, high temperature and high pressureand the like, the wear failure of the mechanical part is particularlysevere. Therefore, the surface of the mechanical part that has afriction pair is required to have high hardness and wear resistanceduring use. The surface engineering technology can make a wear-resistantcoating with superior performance. The coating material is usually acomposite material, and the reinforced phase mainly is carbide, borideand nitride with high hardness and wear resistance. Co₃W₃Cfish-bone-shape hard phase does not exist in the reinforced phase of thecurrent wear-resistance coating and is not used as the reinforced phaseof the wear-resistant coating.

CONTENT OF THE INVENTION

The present invention is aimed to provide an Co₃W₃C fish-bone-shapehard-phase reinforced Fe-based wear-resistant coating and preparationthereof, which has a simple and convenient operation process and acladding layer that is uneasy to break off.

The technical solution for realizing the purpose of the presentinvention is as follows: The wear-resistant coating and preparationmethod thereof: use a plasma cladding process to clad the Fe-based WCalloy powder on the surface of a metal matrix to form a wear-resistanthigh hardness coating with fish-bone-shape Co₃W₃C as the reinforcedphase;

The Fe-based WC mixed alloy powder has the following components inweight percentage: C: 1.89-3.77%, Cr: 5.4-11.7%, Ni: 3.3-7.15%, W:28.81-57.83%, Co: 4.2-8.4%, Si: 0.03-0.065%, and the remaining is Fe;

The plasma cladding process has the following specific steps:

(1) Pre-treatment of the matrix:

Polishing the surface of the matrix to remove an oxide layer, placingthe treated matrix on a plasma cladding working table, and adjusting itsposition;

(2) Pre-treatment of the alloy powder:

Screening the WC powder with granularity of 280-320 meshes and theFe-based alloy powder of 100-200 meshes, preparing the Fe-based WC mixedalloy powder with the mentioned weight percentage, putting in a stirrerto stir for 50-60 min, putting in a drying oven to heat at 150° C., andputting in a plasma cladding machine after finishing the abovepre-treatments;

(3) Plasma cladding:

The plasma cladding process includes the following technical parameters:A working current of 135-145 A, a working voltage of 11-12 V, powderfeeding gas and protecting gas are argon gas, powder feeding gaspressure of 280-300 MPa, protecting gas pressure of 700-800 MPa,distance from a nozzle to the surface of the matrix is 10 mm, and ascanning speed of 80 mm/min.

(4) Treatment of cladding layer:

After finishing the plasma cladding process, turning off the plasmacladding machine, cutting the side and the front of the cladding layer,grinding and polishing, and fish-bone-shape hard phase can be observedunder an optical microscope and an electron microscope; in conjunctionwith the X ray diffraction analysis result, the hard phase is identifiedas Co₃W₃C, which exhibits high performance in a hardness test and a wearresistance test.

The beneficial effects: due to the above-mentioned solution, themetallurgical bonding performance of the cladding layer obtained usingthe plasma cladding technology and the matrix material is superior, theoperation process is simple and convenient, and the cost of equipment islow. The plasma cladding process is used to prepare Fe-based WC alloypowder to obtain the Co₃W₃C fish-bone-shape hard-phase reinforcedFe-based wear-resistant coating and preparation method thereof, wherethe reinforced phase is Co₃W₃C fish-bone-shape carbide, the carbide hashigh hardness (micro hardness HV=888−1097) and high wear resistance. Thefollowing feature is obtained: the cladding layer with the reinforcedphase of fish-bone-shape hard phase Co₃W₃C has high hardness and highwear resistance; and the cladding layer is uneasy to break off.Therefore, the present invention has high application value andinnovation significance.

The present invention is advantaged in:

(1) The plasma cladding process is simple, the equipment is convenientto operate, the economic benefit is high, and the process can be widelyused for surface reinforcement of a precision parts.(2) Adopting the above process scheme, the bonding performance of theresulting cladding layer and the matrix is superior, the optimalperformance matching between the ceramic phase of the cladding layer andthe matrix can be realized, and the comprehensive physical property ofthe matrix structure is greatly improved.(3) The fish-bone-shape reinforced phase Co₃W₃C has features of highhardness and high wear resistance, improves the hardness of the claddinglayer, reduces the wear of the matrix structure as the framework of thecladding layer in friction, and efficiently improves the use value ofthe matrix.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an XRD graph of a plasma cladded wear-resistant coating of thepresent invention.

FIG. 2 is a metallographic structure graph of a plasma cladding layer ofthe present invention under an optical microscope.

FIG. 3 is a metallographic structure graph of the plasma cladding layerof the present invention under an electron microscope.

FIG. 4 is morphology of 100 micrometer of the plasma cladding layer ofthe present invention after a wear test.

FIG. 5 is morphology of 30 micrometer of the plasma cladding layer ofthe present invention after a wear test.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The specific embodiment of the present invention is further describedbelow in conjunction with the accompanying drawings:

The wear-resistant coating and preparation method thereof of the presentinvention: use a plasma cladding process to clad the Fe-based WC alloypowder on the surface of a metal matrix to form a wear-resistant highhardness coating with fish-bone-shape Co₃W₃C as the reinforcement phase;

The Fe-based WC mixed alloy powder has the following components inweight percentage: C: 1.89-3.77%, Cr: 5.4-11.7%, Ni: 3.3-7.15%, W:28.81-57.83%, Co: 4.2-8.4%, Si: 0.03-0.065%, and the remaining is Fe;

The plasma cladding process has the following specific steps:

(1) Pre-treatment of the matrix:

Polishing the surface of the matrix to remove oxide layer, placing thetreated matrix on a plasma cladding working table, and adjusting itsposition;

(2) Pre-treatment of the alloy powder:

Screening the WC powder with granularity of 280-320 meshes and theFe-based alloy powder of 100-200 meshes, preparing the Fe-based WC mixedalloy powder with the mentioned weight percentage, putting in a stirrerto stir for 50-60 min, putting in a drying oven to heat at 150° C., andputting in a plasma cladding machine after finishing the abovepre-treatments;

(3) Plasma cladding:

The plasma cladding process includes the following technical parameters:A working current of 135-145 A, a working voltage of 11-12 V, powderfeeding gas and protecting gas are argon gas, powder feeding gaspressure of 280-300 MPa, protecting gas pressure of 700-800 MPa,distance from a nozzle to the surface of the matrix is 10 mm, and ascanning speed of 80 mm/min.

(4) Treatment of a cladding layer:

After finishing the plasma cladding process, turning off the plasmacladding machine, cutting the side and the front of the cladding layer,grinding and polishing, and fish-bone-shape hard phase is observed underoptical microscope and electron microscope; in conjunction with the Xray diffraction analysis result, the hard phase is identified as theCo₃W₃C, which exhibits high performance in a hardness test and a wearresistance test.

Example 1

The surface of the matrix is polished to remove oxide layer, the treatedmatrix is placed on a plasma cladding working table, and its position isadjusted.

The WC powder with granularity of 280-320 meshes and the Fe-based alloypowder of 100-200 meshes are screened to prepare the Fe-based WC mixedalloy powder including the following components in weight percentage: C:3.24%, Cr: 7.2%, Ni: 4.4%, W: 49.56%, Co: 7.2%, Si: 0.04%, and theremaining is Fe. The powder is subjected to pre-treatment, put in astirrer to stir for 50-60 min, put in a drying oven to heat at 150° C.,and put in a powder feeder. The cladding process includes: A workingcurrent of 140 A, a working voltage of 11 V, powder feeding gas andprotecting gas are argon gas, a powder feeding gas pressure of 300 MPa,a protecting gas pressure of 800 MPa, distance from a nozzle to thesurface of the matrix is 10 mm, and a scanning speed of 80 mm/min. Theplasma cladding machine is turned off after finishing the cladding, theworkpiece is naturally cooled to room temperature in the air.

Mutual-rubbing test is performed on an M-200 wear testing machine forthe prepared Co₃W₃C fish-bone-shape hard-phase reinforced Fe-basedwear-resistant coating with a wear time of 40 min and a wear amount of0.008 g, while under the same conditions, Q235 steel has a wear amountof 0.1996 g, the wear resistance is significantly improved, the highesthardness value is up to 946 HV, and the hardness value is alsosignificantly improved.

In FIG. 2, it can be seen that a large amount of fish-bone-shape hardphase is distributed on the matrix; and in FIG. 3, it can be obviouslyseen that the framework structure of the structure serves as awear-resistant framework, reduces the wear of the matrix structure andimproves the wear resistance in the friction test.

Example 2

The pre-treatment process of the matrix is kept the same as that ofExample 1, and the prepared Fe-based WC mixed alloy powder includes thefollowing components in weight percentage: C: 3.77%, Cr: 5.4%, Ni: 3.3%,W: 57.83%, Co: 8.4%, Si: 0.03%, and the remaining is Fe. The processparameters of the plasma cladding are the same as those of Example 1,and a cladding layer with a superior performance can be obtained.

Mutual-rubbing test is performed on the M-200 wear testing machine forthe prepared Co₃W₃C fish-bone-shape hard-phase reinforced Fe-basedwear-resistant coating with a wear time of 40 min, a wear amount of0.0032 g and a very superior wear resistance. FIG. 1 is an XRD graph ofthe plasma cladding layer of Example 2, the Co₃W₃C in the cladding layerplays a big role in improving the performance thereof. In FIG. 4, it canbe seen that a large amount of fish-bone-shape hard phase Co₃W₃C on awear surface is embossed on the surface of the matrix.

Example 3

The pre-treatment process of the matrix is kept the same as that ofExample 1, and the prepared Fe-based WC mixed alloy powder includes thefollowing components in weight percentage: C: 1.89%, Cr: 11.7%, Ni:7.15%, W: 28.81%, Co: 4.2%, Si: 0.065%, and the remaining is Fe. Theprocess parameters of the plasma cladding are the same as those ofExample 1, and a cladding layer with a superior performance can beobtained.

1. A Co₃W₃C fish-bone-shape hard-phase reinforced Fe-basedwear-resistant coating, characterized in that: the wear-resistantcoating consists of the following alloy powder elements in weightpercentage: C: 1.89-3.77%, Cr: 5.4-11.7%, Ni: 3.3-7.15%, W:28.81-57.83%, Co: 4.2-8.4%, Si: 0.03-0.065%, and the remaining is Fe. 2.A method for preparing the Co₃W₃C fish-bone-shape hard-phase reinforcedFe-based wear-resistant coating according to claim 1, characterized inthat: a plasma cladding process is used to clad the Fe-based WC alloypowder on a surface of a metal matrix to form a wear-resistant highhardness coating with fish-bone-shape Co₃W₃C as the reinforcement phase;the specific steps are as follows: A pre-treatment of the matrix:polishing the surface of the matrix to remove oxide layer, placing thetreated matrix on a plasma cladding working table, and adjusting itsposition; B pre-treatment of the alloy powder: screening the WC powderwith granularity of 280-320 meshes and the Fe-based alloy powder of100-200 meshes, preparing the Fe-based WC mixed alloy powder of thementioned weight percentage, putting in a stirrer to stir for 50-60 min,putting in a drying oven to heat at 150° C., and putting in a plasmacladding machine after finishing the above pre-treatments; C plasmacladding: the plasma cladding process includes the following technicalparameters: a working current of 135-145 A, a working voltage of 11-12V, powder feeding gas and protecting gas are argon gas, a powder feedinggas pressure of 280-300 MPa, a protecting gas pressure of 700-800 MPa,distance from a nozzle to the surface of the matrix is 10 mm, and ascanning speed of 80 mm/min; and D treatment of a cladding layer: afterfinishing the plasma cladding process, turning off the plasma claddingmachine, cutting the side and the front of the cladding layer, grindingand polishing, and fish-bone-shape hard phase is observed under anoptical microscope and an electron microscope; in conjunction with the Xray diffraction analysis result, the hard phase is identified as Co₃W₃C,which exhibits high performance in a hardness test and a wear resistancetest.